Article and method for preventing escape of pyrophoric material

ABSTRACT

A method and an article to be encapsulated in which a relatively small cartridge containing a substance which is spontaneously combustible is completely sealed and enclosed in the encapsulating material. The encapsulating material can be a polyamide mixture having a tear strip embedded therein whereby a sharp pull on the strip will quickly release the cartridge from the encapsulating mechanism.

United States Patent mi Mackness et al.

[ 1 Jan. 23, 1973 ARTICLE AND METHOD FOR [56] References Cited PREVENTING ESCAPE OF Inventors; Frederich Vincent Summersford 3,535,065 l0/l970 Guenin ..43l/267 Mackness; o Norman Cheetham, 3,204,385 9/1965 Deremer et al ..53/36 X b f Ashtead; vi J w 3,377,955 4/1968 HOdgSOlI "86/1 R X son, Tolworth, all of England Ronson Corporation, Woodbridge, NJ.

Filed: Feb. 22, 1971 Appl. No.: 117,244

Primary ExaminerBenjamin A. Borchelt Assignee: Assistant Examiner-H. J. Tudor [57] ABSTRACT A method and an article to be encapsulated in which a relatively small cartridge containing a substance which is spontaneously combustible is completely sealed and Forms Application Prlomy Dam enclosed in the encapsulating material. The encapsu- Feb. 26, 1970 Great Britain ..9,485/70 lating material can be a, polyamide mixture having a tear strip embedded therein whereby a sharp pull on US. Cl ..86/l, 431/267 the strip i quickly release the cartridge f the Int-Cl. ..C06b 21/02 capsulating mechanism Field of Search ..86/l; 431/267; 53/36, 14

12 Claims, 2 Drawing Figures m /2 2? [a Z5 Z4 Z3 Z6 I I V '//j l 7 W N i- "1 a p I X: l v VI 2220 v A j//// 7)//////// a a ARTICLE AND METHOD FOR PREVENTING ESCAPE OF PYROPIIORIC MATERIAL A cartridge has been developed which contains a pyrophoric substance such as a spontaneously combustible compound therein such as aluminum borohydride. A cartridge of this type is depicted in US. Pat. No. 3,535,065 entitled Igniter Cartridge" and granted on Oct. 20, 1970. Cartridges of this type have a small orifice through which a minute quantity of the pyrophoric substance is discharged when the cartridge is struck or otherwise actuated. In order to achieve this effect the cartridge contains an actuating mechanism which, in its inoperative condition, maintains the orifice sealed to prevent leakage. In use, this mechanism has been found to be completely reliable. However, should it be necessary to transport cartridges containing the pyrophoric substance by mail or by air, then it may be considered that the sealing of these cartridges is inadequate for postal or air freight rules and additional means may be required to insure that the pyrophoric substance will not be accidentally ejected.

Accordingly, the invention contemplates that such a cartridge be encapsulated in a material which is impervious and tire resistant to eliminate the possibility of the pyrophoric substance contacting the outside air. The material must not be easily removed by jarring but must be easily removable by authorized personnel. The material must be light in weight and small in bulk for shipping, packaging and storage purposes. In a preferred form the cartridge is encapsulated in a polyamide mixture having a melting point less than 150 C. but preferably between 90 C. and 120 C., in which the mixture includes at least one additive to render it fire resistant. Other additives impart to the mixture pliability enabling the encapsulation to be easily opened by hand and to prevent the mixture from bonding to the cartridge except by friction.

A tear strip can be embedded within the encapsulating mixture whereby the encapsulating body may be torn open to expose the cartridge housed therewithin when desired.

The objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, reference may be had to the accompanying drawings in which:

FIG. 1 is a cross section of the encapsulated cartridge, and

FIG. 2 is an end view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 there is shown an encapsulated cartridge 10. The cartridge 12 itself is wholly enclosed within an outer sheath 11. The cartridge 12 is adapted to be used as an ignition mechanism to ignite a fuel such as butane. A housing 13 having an open interior forms the outer walls of the cartridge 12. The housing 13 is closed at the rear portion by means of an end plug 14 which can have a flanged end 15 extending beyond the periphery of the housing 13. The end plug 14 has a grooye 16 formed therein for the reception of an o-ring or other elastomeric seal 17. End cap 14 is secured to the housing 13 by crimping the end of the housing thereby forming a circumferential detent 18 which firmly bears against the sealing member 17. The front portion of the housing 13 has a tapered orifice 19 bored therein and sized to receive a correspondingly tapered orifice pin 20. The pin 20 is secured to a plunger 21.

The plunger 21 includes a hollow chamber 22 and a shoulder 23 formed on the exterior surface of the plunger. An absorbent material 24 which can be Kaowool or any other suitable absorbent material is packed into the plunger 21. The absorbent is saturated with a spontaneously ignitable substance such as aluminum borohydride AI(BH Small passageways 25 in the plunger 21 allow the aluminum borohydride vapors to advance to the front of the cartridge and exit through the orifice 19 when the pin 20 is withdrawn. A coiled spring 26 has one end thereof resting on the shoulder 23 of the plunger and the other end bears against the end plug 14 such that the spring is under compression. The spring thereby urges the plunger 21 toward the front of the housing 13 and the pin 20 is forced to seat within the tapered orifice 19 and thereby seal the orifice.

To operate the cartridge 12 and thereby eject the pyrophoric substance an impact force is applied to the forward face of the cartridge. The plunger 21 is forced rearwardly by the mass of the plunger 21 further compressing the spring 26. As the plwnger 21 moves rearwardly, the pin 20 is withdrawn slightly from the orifice l9 and a minute amount of the pyrophoric substance is ejected which ignites spontaneously producing a flash of heat sufficient to ignite a fuel such as butane. The

opening is quickly sealed by the pin 20 being forced into the orifice 19 by the spring 26. Thus, the cartridge 12 can be placed in a butane cigarette lighter and the pyrophoric substance emitted therefrom can be used to ignite the fuel emanating from the burner valve in a cigarette lighter as shown and described in US. Pat. No. 3,360,965 entitled Gas Lighter" and issued on Jan. 2, 1968.

It is obvious that cartridges of this type must be handled relatively carefully because they can be made to produce a small flame when they are mishandled. In order to insure against the hazards which can result from mishandling the cartridge, it is completely immersed in a sealing substance which is fireproof, impervious to air and can be readily removed by the consumer and also gives the added advantage of shock proofing the cartridge. To accomplish encapsulation of the cartridge 12, a mixture is initially prepared comprising a polyamide chosen from a group having a flexible molecular chain. A chlorinated diphenyl is added followed by the addition of ester wax and then n-butyl stearate. The mixture is then heated so as to form a slurry in the following proportions: 54% Polyamide, 32% Chlorinated Diphenyl, 11% Ester Wax and 3% n- Butyl Stearate.

The mixture is preferably maintained at a temperature between C. and C. The cartridge 12 is completely immersed in the viscous slurry for approximately 1 to 2 seconds and the coating 11 is then al' lowed to cure at room temperature for approximately 15 to 20 seconds during which the coating 11 solidifies toa fairly uniform thickness of between 1/16 to A; inch and has a plastic or rubber-like texture. A more rapid setting time can be obtained if the cartridge is chilled prior to immersion in the slurry. Chilling also reduces the risk of any harmful effects by heat on the cartridge.

If it is desired to imbed a tear strip in the coating 28, to facilitate the removal of the coating from the cartridge, a strip of glass fiber-self-adhesive tape 27 can be wrapped around the cartridge prior to dipping the cartridge in the slurry. The tape 27 is wrapped around the cartridge one to three times and the end is left extending about one-half inch beyond the periphery of the cartridge. This portion of the tape 27 will not be imbedded in the slurry and the user of the device merely pulls on the free end of the tape to tear open the covering on the cartridge when the coating has cured.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention, and therefore, it is intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

We claim:

1. An encapsulated cartridge containing a pyrophoric substance therein comprising,

a. a housing having a closed end and having an orifice bored in the opposite end,

b. actuating means in said housing for selectively opening and closing said orifice,

c. a pyrophoric substance within said housing located such that it can pass through said orifice in a minute quantity when the actuating means opens the orifice,

d. a relatively thin impervious-removable-encapsulating sheath closely surrounding said housing so as to prevent the egress of any pyrophoric substance which may escape from the housing.

2. A cartridge as defined in claim 1 in which said pyrophoric substance is aluminum borohydride.

3. A cartridge as defined in claim 1 in which said means for selectively opening and closing said orifice is a plunger, a tapered pin on the end of said plunger which reciprocates within the open end of the housing to selectively open and close said opening and spring means within said housing biasing said plunger and pin into closed position.

4. A cartridge as defined in claim 1 in which said encapsulating sheath wholly encloses said cartridge.

5. A cartridge as defined in claim 1 in which said encapsulating sheath is a polyamide.

6. A cartridge as defined in claim 1 in which said encapsulating sheath is comprised ofa mixture of approximately 54 percent polyamide, 32 percent chlorinated diphenyl, 11 percent ester wax and 3 percent n-butyl stearate.

7. A method for encapsulating a cartridge comprising the steps of a. filling a cartridge with a pyrophoric substance,

which can be ejected from said cartridge,

preparing a slurry so as to form an encapsulated material which is impervious to air and moisture and is fireproof,

c. immersing said cartridge in said slurry until the slurry coats the surface of the cartridge, d. removing the cartridge from the slurry and,

e. allowing said encapsulating material coating the cartridge to cure.

8. A method for encapsulating a cartridge as defined in claim 7 in which the pyrophoric substance is aluminum borohydride.

9. A method for encapsulating a cartridge as defined in claim 7 in which the slurry is comprised of approximately 54 percent polyamide, 32 percent chlorinated diphenyl, ll percent ester wax and 3 percent n-butyl stearate. Y

10. A method for encapsulating a cartridge as defined in claim 7 including the step of maintaining the cartridge in the slurry for approximately 1 to 2 seconds.

11. A method for encapsulating a cartridge as defined in claim 7 including the step of securing a tear strip to the cartridge to facilitate the removal of the cured encapsulating material.

12. A method for encapsulating a cartridge as defined in claim 7 including the step of chilling the cartridge prior to immersing the cartridge in the slurry. 

2. A cartridge as defined in claim 1 in which said pyrophoric substance is aluminum borohydride.
 3. A cartridge as defined in claim 1 in which said means for selectively opening and closing said orifice is a plunger, a tapered pin on the end of said plunger which reciprocates within the open end of the housing to selectively open and close said opening and spring means within said housing biasing said plunger and pin into closed position.
 4. A cartridge as defined in claim 1 in which said encapsulating sheath wholly encloses said cartridge.
 5. A cartridge as defined in claim 1 in which said encapsulating sheath is a polyamide.
 6. A cartridge as defined in claim 1 in which said encapsulating sheath is comprised of a mixture of approximately 54 percent polyamide, 32 percent chlorinated diphenyl, 11 percent ester wax and 3 percent n-butyl stearate.
 7. A method for encapsulating a cartridge comprising the steps of a. filling a cartridge with a pyrophoric substance, which can be ejected from said cartridge, b. preparing a slurry so as to form an encapsulated material which is impervious to air and moisture and is fireproof, c. immersing said cartridge in said slurry until the slurry coats the surface of the cartridge, d. removing the cartridge from the slurry and, e. allowing said encapsulating material coating the cartridge to cure.
 8. A method for encapsulating a cartridge as defined in claim 7 in which the pyrophoric substance is aluminum borohydride.
 9. A method for encapsulating a cartridge as defined in claim 7 in which the slurry is comprised of approximately 54 percent polyamide, 32 percent chlorinated diphenyl, 11 percent ester wax and 3 percent n-butyl stearate.
 10. A method for encapsulating a cartridge as defined in claim 7 including the step of maintaining the cartridge in the slurry for approximately 1 to 2 seconds.
 11. A method for encapsulating a cartridge as defined in claim 7 including the step of securing a tear strip to the cartridge to facilitate the removal of the cured encapsulating material.
 12. A method for encapsulating a cartridge as defined in claim 7 including the step of chilling the cartridge prior to immersing the cartridge in the slurry. 